There has been speculation since the mid-1940's that coffee contains a gastric acid secretagogue (a stimulant of the production of digestive acid in the stomach) distinct from its caffeine content That early research has been reconfirmed over the years by numerous investigators who showed that decaffeinated coffee retains a majority of coffee's ability to increase the secretion of acid by the stomach
Normal food intake leads to gastric acid secretion because of the action of only a few food constituents and the direct effect of stomach distention. Caffeine, coffee, calcium ions, alcohol and the digestion products of protein are the only commonly ingested food components known to increase gastric acid output The gastric acid secretagogue component of decaffeinated coffee has been the subject of speculation and debate throughout the scientific community.
Early attempts in the food art to produce a "stomach friendly" coffee, that is a coffee which will produce less or no heartburn in susceptible individuals, centered upon the deacidification of coffee such as by chemically neutralising the acids present in coffee by the addition of a food-grade alkaline agent.
Farr and Horman (U.S. Pat. Nos. 4,160,042 and 4,204,004) teach a method of reducing the caffeine and/or chlorogenic acid content of coffee by treatment with particles of carob pods which absorb the caffeine and chlorogenic acid. Magnolato (U.S. Pat. No. 4,278,696) teaches a process for deacidifying a coffee extract by contacting it with chitosan in divided form and recovering the resultant deacidified extract. This patent stresses the importance of the removal of chlorogenic acid since it is the predominant acid found in coffee. However, other acids including malic acid are also reduced by the treatment. Another process, described in U.S. Patent No. 4,317,841 to Brambilla and Horman, teaches the reduction in the acidity of a coffee extract by electrodialysis. The non-cathodic extract is collected, contacted with subdivided chitosan and, after removal of the chitosan, is mixed with at least a part of cathodic extract to provide a deacidified coffee extract.
DE No. 3,239,219 having a disclosure date of Apr. 26, 1984 entitled "Process for the Reduction of the Chlorogenic Acid Content of Raw Coffee" teaches a process involving the contacting of an aqueous extract of green coffee beans with a polymer anion-exchange resin, this resin having been loaded by adsorption with at least one nonacidic coffee extract constituent in order to exchange the acids present in the aqueous extract to produce a reduced chlorogenic acid green coffee. The object of this invention is to produce a coffee product which would reduce irritation of stomach mucosa and not cause stomach acidity.
PCT International Publication Number WO 87/04598 having a publication date of Aug. 13, 1987 entitled "Coffee And Process For Its Production" teaches a coffee product with an increased chlorogenic acid content. This elevated chlorogenic acid level is said to improve the digestibility of coffee by reducing human acid secretion. The physiology studies reported in the patent application were performed on human male and female subjects. However, the p or methodology utilized in the studies including the lack of proper scientific controls render the results questionable at best.
There remains a need in the art to produce a stomach friendly coffee by selectively removing malic acid and without sacrificing the large percentage yield loss and flavor penalty which results from the removal of a majority of chlorogenic acid as taught by prior art references.